It will pay the next £60m of drilling costs and a further £60m to Cuadrilla and its partner AJ Lucas if drilling succeeds and the companies begin development. Cuadrilla was advised by Jefferies on the deal.

Asked if Mr Laidlaw would have to eat his words, Mr Egan said: “We would hope so. I’m sure he is not going to be saying that to his employees now.”

Cuadrilla’s “conservative” estimate of the gas in the ground is 200 trillion cubic feet. Even if only 10pc could be extracted, it would be equivalent to nearly seven years’ of UK usage.

“This is a huge resource, this has the potential to go into millions of houses in the UK,” Mr Egan said.

Centrica maintained a note of caution on Thursday, pointing out it was not yet known whether shale gas would be commercial to develop.

But executive Mark Hanafin said: “With North Sea gas reserves declining and the UK becoming more dependent on imported gas supplies, it is important that we look for opportunities to develop domestic gas resources, to provide affordable sources of gas to our customers, and to deliver broader economic benefits to the UK.”

Mr Egan dismissed fears that fracking would require “industrialising the landscape”. He said 100 drilling sites of two hectares each should be “more than adequate” to extract 20 tcf of gas - occupying “a total surface footprint of 2km² across a licence area of 1200km²”.

A Cuadrilla-commissioned report by Deloitte, released on Thursday, said that shale gas in the Bowland could generate £580m of tax revenue a year and reduce gas import needs by 14pc by 2020, as well as supporting up to 23,600 jobs.

Cuadrilla will need to win planning consent before it can drill at any of the new sites, or to frack to test its existing wells. Fracking involves blasting water, sand and chemicals into the ground and is opposed by green groups who fear environmental damage.

Cuadrilla caused two small earth tremors while fracking near Blackpool in 2011, leading to an 18-month ban. However, new rules mean it must stop fracking if it causes a tremor of 0.5 on the Richter scale. Mr Egan said that was equivalent to “a bus going outside your door”.

He called on the government to help combat “scare stories”.

Analysts welcomed Centrica’s move, which they said made strategic sense. However, UBS warned it was “not without some reputational risk.”

Friends of the Earth said: “Buying into Cuadrilla is about the only way Centrica could make itself even more unpopular with the public, who are fed up with the company raking in huge profits on the back of rocketing fuel bills."